Distribution and determinants of the difference between diastolic phase 4 and phase 5 blood pressure.

Auscultatory blood pressure measurements from 18 325 male British civil servants were used to examine the relationship between diastolic phase 4 (D4) and phase 5 (D5). The two measures are highly correlated (r = 0.98) and this is unaffected by age. The distribution of the difference between the two indices is skewed with a median difference of 1 mmHg. Phase 4 and D5 were recorded at the same level in 31% of subjects. The difference was 5 mmHg or more in 9% of subjects, and 10 mmHg or more in 1%. The difference between the two diastolic indices depends partly on the level of blood pressure and body mass index.